Over the summer I am going to move to Montana, this is great because it means I am only a couple miles away for beautiful locations with almost no light pollution. I have gotten pretty interested in star photography and I really want to capture the Milky Way. I shoot with a Canon 5D MKII and I have a 17-40mm f/4 and 50mm 1.8 that I use when I do photograph the night sky. I have been wondering what would be a good lens to use for capturing the Milky Way, my 50mm seems a bit to long and my 17-40mm seems to slow. I've been thinking about getting a Rokinon 14mm 2.8 because it is wider so I can use a longer shutter speed without getting star trails and faster so I can use a lower ISO. Having it be manual focus wouldn't seem to be that much of a problem if the infinity is well marked. I'm just looking for other peoples inputs on what they think would be a good alterative to my two lens or if one of the lenses I already have would be well suited for this. Here are some shots I've gotten why in Hawaii and in Montana, unluckily, it was cloudy every night for 2-5 so I never got a chance to get any Milky Way shots.

Over the summer I am going to move to Montana, this is great because it means I am only a couple miles away for beautiful locations with almost no light pollution. I have gotten pretty interested in star photography and I really want to capture the Milky Way. I shoot with a Canon 5D MKII and I have a 17-40mm f/4 and 50mm 1.8 that I use when I do photograph the night sky. I have been wondering what would be a good lens to use for capturing the Milky Way, my 50mm seems a bit to long and my 17-40mm seems to slow. I've been thinking about getting a Rokinon 14mm 2.8 because it is wider so I can use a longer shutter speed without getting star trails and faster so I can use a lower ISO. Having it be manual focus wouldn't seem to be that much of a problem if the infinity is well marked. I'm just looking for other peoples inputs on what they think would be a good alterative to my two lens or if one of the lenses I already have would be well suited for this. Here are some shots I've gotten why in Hawaii and in Montana, unluckily, it was cloudy every night for 2-5 so I never got a chance to get any Milky Way shots.

I've noticed your images look SIGNIFICANTLY less noisy than mine (taken on a 5D Mk III), what kind of noise-reduction are you using, if any? A lot of your ISO 20k images look better than my 6400 images! (such as this one: http://500px.com/photo/33608607) Are you just using LR's chroma noise reduction?

I've noticed your images look SIGNIFICANTLY less noisy than mine (taken on a 5D Mk III), what kind of noise-reduction are you using, if any? A lot of your ISO 20k images look better than my 6400 images! (such as this one: http://500px.com/photo/33608607) Are you just using LR's chroma noise reduction?

Great website, love the analysis, super-helpful!

Thanks. If you look at the second page linked on there those full size examples have zero noise reduction done other than color. I tried to do some on the smaller sized versions but pretty much it wasn't helping any of them and making them look worse, so most of those don't even have any sized down. But the full sized crops on the second page were left alone to show the noise/lack of noise. Pretty amazing sensor up in those extreme ranges. But a lot of it can just be the scene. Like if you have any haze or fog it will obviously show noise a lot quicker. THis was very clear and so also there are a lot more stars too and that added detail tends to hide noise/make it appear better.

Sorry to quote out of context, but this is directly contrary to what Lensrentals found when they tested the Zeiss 25mm f/2. They found it was not all that sharp, and I assume tested several copies.

Hi Carl - I respect Roger C's knowledge. Nevertheless, LR did a test to find the best lenses for the D800E. Per LR's test the 25/2 is the sharpest lens they have at that focal length... In a different blog post, Roger comments that it may not be the best choice for landscape use. These comments are not consistent with one another. I've also compared RC's results with Lloyd Chambers (www.zeissguide.com - you pay for what you get) and Lloyd's at odds with Roger's assessment.

I guess the only way to check this rigorously is to piggyback my 5D2 and a couple of lenses on my (Tak) mount, focus carefully and shoot some images. Predictably, Toronto will be getting wall-to-wall rain all weekend (and I just realised my camera is still at Canon.)

When stopped down to f/4, the 25/2 is supposed to achieve better than 70% contrast (at 40 lp/mm over an 36 mm diameter disc.)

Translation - At f/4, this lens can reproduce 40 x 36 = 1440 off-to-on-to-off transitions with a contrast of at least 70% over the width of a 135 sized sensor. Mild sharpening in pp can easily improve the contrast if needed.

Stars are essentially points. Assume visible light and f/4, then the smallest disc possible is about 2.4 microns fwhm. Thanks to AA filters, our cameras can really only resolve about 2 pixels, or say 12 microns. Camera lenses don't need to be diffraction limited. This is why I can afford them.

Anyway - the 25/2 easily allows resolution of about 2880 transitions in 36 mm, or 80/mm. This means the resolution width is 12.5 microns. Now the camera can only see 12.5 microns so the 25/2 lens is capable of filling the camera's resolution over the 36 mm disc with 70% or better contrast...

Focusing to this level is achievable - motion of the lens through 10 microns on either side of focus degrades resolution by ~20% . A good loupe and magnified live view make it easy.

For astrophotography - it pays to focus the lens at about halfway to the edge. This helps to deal with focal plane curvature.

Very interesting. I seem to recall Roger's main complaint was that it got too soft closer to wide open at f/2 (I could be remembering wrong). The test at f/4 is fine for f/4...are you saying you do shorter-than-40-second exposures at or around f/4, and just let the noise take its terrible effect?

Can I assume that you are saying the 25 f/2, would be sharper at f/2.8, than the 21mm lens at f/2.8?

The reason I would buy or use either the Zeiss 21 or 25, would be to shoot at wider aperture than f/4...to capture the Milky Way with a minimum of motion and minimum noise. Longer exposure "star trail" photography does not interest me as much.

The only picture of mine that's ever been published was of the Milky Way, shot three years ago with an older Sigma 17-70 on a crop body. The editor commented on the star sharpness I achieved, but thankfully gave me a pass on the noise.